This project is oriented toward applying roentgen contrast techniques to the investigation of the cardiovascular system in a variety of experimental and clinical conditions. It combines the demonstrated capacity for high-grade morphologic display of angiography with physiologic methods to study problems in which the two approaches are required for optimal analysis. A major objective is to place the investigation of the coronary circulation in man on a rational basis pre- and post-operatively. This will be accomplished by parallel studies in animals and man focused on quantitating regional myocardial blood flow and relating it to morphologic changes on the coronary arteriogram. Both dynamic scintiscanning and the particle distribution method will be explored, and a velocity profile of coronary blood flow will be constructed. Myocardial toxicity studies of contrast agents, utilization studies, and analyses of technical approaches will also be performed. A second major area of interest is the renal circulation. These studies are oriented toward defining the intrarenal distribution of blood flow in animal models which resemble oliguric states in man; applying pharmacologic agents to animal models of the pre-glomerular vasoconstriction which appears to characterize acute oliguric states in animals and man; investigating the mediators involved in this vasoconstriction; and ultimately undertaking pharmacologic reversal in acute settings in man. Additional studies are designed to clarify renal vascular responsiveness in essential hypertension and the relative role of fixed vs functional elements in the decreased renal perfusion of nephrosclerosis.